Reciprocating motor

ABSTRACT

A motion electromagnet is provided having a main magnetic circuit with an exciting coil. An auxiliary magnetic circuit under the influence of the magnetic flux of the main magnetic circuit has a movable and a stationary part with movable and stationary windings respectively therein which are off-set with a constant air gap maintained between the stationary and movable parts. Energizing the exciting coil of the main magnetic circuit moves the movable parts of the auxiliary magnetic circuit into alignment with the stationary part. By symmetrically duplicating the main and auxiliary magnetic circuits, and alternately activating the main magnetic circuits via their respective exciting coils by a switching device, an oscillating movement in the electromagnet is produced.

United States Patent [i9] Hrubes et a].

[ RECIPROCATING MOTOR [75] Inventors: Jan Hrubes; Alois Dubansky, both of Prague, Czechoslovakia [73] Assignee: Ceskoslovenska Akademie ved,

Prague, Czechoslovakia [22] Filed: Oct. 25, 1972 [21] Appl. No.: 300,743

[30] Foreign Application Priority Data Oct. 26, 1971 Czechoslovakia 7542/71 [52] U.S. Cl 318/122, 310/27, 310/35 [51] Int. Cl. .L H02k 33/18 [58] Field of Search 310/15, 17, 19, 24, 310/33, 34, 35, 30; 318/122, 123, 129, 119

[56] I References Cited UNITED STATES PATENTS 824,953 7/1906 Schiemann .Q 310/35 2,003,647 6/1935 Dillstrom 318/122 X Basilewsky 4/ 1964 Nowak .I 310/35 Dec. 4, .1973

12/1964 Laithwaite 310/27 7/1969 Wildi ..3l0/27 Primary Examiner-D. F. Duggan Attorney-Arthur O. Klein [57 ABSTRACT A motion electromagnet is provided having a main magnetic circuit with an exciting coil. An auxiliary magnetic circuit under the influence of the magnetic flux of the main magnetic circuit has a movable and a stationary part with movable and stationary windings respectively therein which are off-set with a constant air gap maintained between the stationary and movable parts. Energizing the exciting coil of the main magnetic circuit moves the movable parts of the auxiliary magnetic circuit into alignment with the stationary part. By symmetrically duplicating the main and auxiliary magnetic circuits, and alternately activating the main magnetic circuits via their respective exciting coils by a switching device, an oscillating movement in the electromagnet is produced.

5 Claims, 3 Drawing Figures "PATENIEDUEB 41915 3.777, 236

SHEET 1 OF 2 I mmmmm PATENTED C 4 I975 SHEET 2 0F 2 l RECIPROCATING MOTOR BACKGROUND OF THE INVENTION .order to generate the required force. In addition, the

armature strikes the core with a blow which does not contribute to an extensive life for such an electromagnet.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a motion electromagnet with a high pull force at the start of the motion.

Another object of the invention is to elimate shocks of the electromagnet where it is used for generating vibrations.

Still another object of this invention is to provide an electromagnet with a substantially more uniform pull force than obtained with currently used electromagnets.

In carrying out this invention in one illustrative embodiment thereof a motion electromagnet is provided having a main magnetic circuit with an exciting coil, connected to a source of electric alternating current by way of a switching device. The main magnetic circuit is provided with a pair of coaxial shortcircuited secondary turns, one turn being stationary and the other turn being movable with respect to the first in the direction of their common axis. An auxiliary magnetic core or circuit encompasses the pair of coaxial secondary turns, and consists of a stationary part, encompassing a part of the stationary secondary turn and of a movable part, encompassing a part of the movable secondary turn, with a constant air gap between both parts of the auxiliary magnetic circuit. The main and auxiliary magnetic circuits are symmetrically duplicated and alternatively actuated by said source via said switching means for providing an oscillating motion in the electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS FIG] is a cross-sectional view of one embodiment of the electromagnet of the present invention taken along lines II of FIG.2.

FIG.2 is a cross-sectional view, the left-hand portion of which is taken along lines IIlI of FIG.3 and the right-hand portion of which is taken along lines Il'II' of FIG.3.

FIG.3 is a cross-sectional view of FIG] taken along line Ill-lll.

DESCRIPTION OF PREFERRED EMBODIMENTS In the embodiment chosen for purposes of disclosure, an electromagnetic device is described utilizing duplicate symmetrical magnetic and electrical structure for providing an oscillating motion which would constitute the more complex form of the present invention. For ease of disclosure and understanding, like elements, even though duplicated, are designated with the same reference characters. For the simple applications, for example to operate a cut-in or cut-out contactor, only one part of the duplicate symmetrical electromagnetic structure would be required which employ the same operating principle.

The motion electromagnet shown in the drawings has two mutually electrically and magnetically independent magnetic circuits 1 with exciting coils 2. The exciting coils 2 are alternately connected by a conventional switching device in the required rhythms to a source 16 of alternating current. In FIG.2 this switching device is indicated schematically as a changeover switch 15. Both main magnetic circuits 1 are either mutually directly fixed, or maintained at a distance by connecting pieces or spacers 11 (see FIG.2).

Each of these main magnetic circuits 1 is provided with a pair of coaxial short-circuited secondary turns or windings 3 and 4, the turns 3 being stationary and the turns 4 being shiftable or movable with respect to turns 3 in the direction of their common axis. Each pair of secondary turns 3 and 4 are encompassed by an auxiliary magnetic circuit 5 and 6, respectively, consisting of a stationary core or part 5 encompassing a part of the stationary secondary turn 3 and fixed to the main magnetic circuit 1 by brackets 17 of non-magnetic material (see FIG.2,3) and of a mobile or movable core or part 6 encompassing a part of the mobile secondary turn 4. The movable core 6 is posited for linear movement on and guided by guidings 12 (see FIG.1), positioned between both secondary turns 3 and 4 and enabling a mutually free movement of both turns 3 and 4 in the direction of their common axis. The arrangement can, however, be easily modified to provide for a swinging motion of the movable core 6 by suspending the mobile core 6 (not illustrated) or supporting it by means of bearings (not illustrated). The auxiliary magnetic circuits 5 and 6 are closed via a constant air gap 7, whereby both their stationary parts 5 and their mobile parts 6 have the shape of a horse shoe (see F163) and the gaps of the horse shoes are occupied by the secondary turns 3 and 4. The air gap 7 is as small as possible with a distance of 0.2 mm being generally sufficient. A pair of short-circuited auxiliary turns 8 and 9 are embedded into the surfaces of the magnetic circuits 5 and 6 forming the air gap 7. The auxiliary turns 8 and 9 perform the function of suppressing vibrations generated by the frequency of the alternating feeding current. The corresponding auxiliary turns 8 and 9 on the stationary and mobile parts 5 and 6 of the auxiliary magnetic circuits are in register or alignment when the stationary and mobile secondary turns 3 and 4 are in register. This case is indicated in the right part of FIG.3. The mobile turns 4 and mobile parts 6 of the auxiliary magnetic circuits corresponding to both main magnetic circuits 1 are mutually connected by adjustable connecting elements 10, by'means of which the magnitude of their deviation with respect to the stable secondary turns 3 and parts 5 of the auxiliary magnetic circuits can be adjusted. For cases of extreme deviations stops 14 are provided on the main magnetic circuits 1 (see FIG.2) which are, however, normally out of action or not used. The movable parts 6 are spaced from the cores 1 by the gap 13 (F101).

The arrangement operates as follows:

3 Alternating electric current is applied by the switching device 15 from the source 16 alternately exciting coils 2 of the main magnetic circuits 1. The switching device 15 is advantageously adapted to enable the adjustment of the switching-over from relatively low speeds up to speeds corresponding to the resonant frequency of the arrangement, to which the vibrating movement has to be transmitted. The switching device 15 can be based on any suitable known principle, for instance being driven by an electric motor or by a suitable conventional electronic circuit for accomplishing the desired switching function and can include conventional switching speed adjusting means 15'. The introduction of current into the exciting coil 2 of the main magnetic circuit 1 causes generation of currents in both secondary turns 3 and 4 which induce magnetic fluxes in the auxiliary magnetic circuits 5 and 6 and tends to bring parts 5 and 6 thereof into alignment. As similar parts of the second auxiliary magnetic circuit are offset with respect to corresponding parts of the first auxiliary magnetic circuit, an attractive force is generated alternately in one and the other direction conforming with the speed of switching-over of the switching device carrying an oscillatory moment of the movable parts. The pull force acts thereby solely up to the moment until both corresponding parts of the auxiliary magnetic circuit come in register or alignment and in case this position is exceeded, a braking force is automatically generated. The arrangement needs therefore for normal operating conditions no stops, as the amplitude of the oscillations is automatically adjusted according to the mutually off-setting of both mobile parts 6 of the auxiliary magnetic circuits, which has already been adjusted using element 10 according to the required amplitudes. The speed of switching-over of the exciting coils 2 of both main magnetic circuits 1 is subsequently increased until the resonant frequency of the driven arrangement is achieved. The feeding current for the exciting coils 2 is relatively small causing no difficulty in switching over from one side to the other.

The described embodiment is namely an example of one form of the invention for achieving the objects of this invention. It is obvious that both the main and auxiliary magnetic circuits can be adjusted differently for oscillations in a straight direction or for oscillations in the shape of swinging around a common axis, while maintaining a constant air gap, without deviating from the scope of this invention.

Where it is desired that the motion electromagnet has to secure some constant position of some part, for instance a constant position of a cut-in or cut-out contactor, operating in a medium, where it is exposed to vibrations so that there is a possibility that its position could be unfavorably influenced by these vibrations, a single main magnetic circuit 1 with a pair of secondary turns 3 and 4 and the respective auxiliary magnetic circuit 5 and 6 can be provided. Thus, only one-half the symmetrical magnetic and electrically operated structure shown in the drawings would be-employed. The

operation of the arrangement remains substantially the Since the modifications and changes varied to fit particular operating requirements and environments, as will be apparent to those skilled in the art, this invention is not considered limited to the examples chosen for purposes of illustration and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

What is claimed is: I

l. A motion electromagnet having a constant air gap and an increased initial pull force comprising a. a main magnetic circuit having an exciting coil for generating a magnetic flux in said main magnetic circuit;

b. a source of potential;

c. switch means coupled between said source of potential and said exciting coil for selectively actuating said exciting coil;

d. first and second short-circuited, mutually coaxial secondary turns magnetically coupled to said main magnetic circuit, said first secondary turns being stationary and said second secondary turns being mobile with respect to said first secondary turns in a direction of their common axis;

e. an auxiliary magnetic circuit encompassing both said first and secondary turns having a stationary part encompassing a part of said first secondary turns and a mobile part encompassing a part of said secondary turns; and

f. a constant air gap separating said stationary and mobile part of said auxiliary magnetic circuit.

2. The motion electromagnet as set forth in claim 1, having auxiliary turns embedded in surfaces creating the air gap of the auxiliary magnetic circuit.

3. The motion electromagnet as set forth in claim 1, wherein the relative movement of stationary and mobile parts of said auxiliary magnetic circuit and said first and second secondary turns is linear.

4. The motion electromagnet as set forth in claim 1 comprising two mutually electrically and magnetically independent main magnetic circuits each having an exciting coil, said switching means alternatively connecting said= exciting coils of said ,two main magnetic circuits to said source of potential at a predetermined rate, a pair of said auxiliary magnetic circuits, adjustable means coupling the mobile parts of said two auxiliary magnetic circuits for adjusting their off-set positions with respect to the corresponding stationary parts of said auxiliary magnetic circuits.

5. The motion electromagnet as set forth in claim 4, including means for adjusting the speed of said switch means. 

1. A motion electromagnet having a constant air gap and an increased initial pull force comprising a. a main magnetic circuit having an exciting coil for generating a magnetic flux in said main magnetic circuit; b. a source of potential; c. switch means coupled betweeN said source of potential and said exciting coil for selectively actuating said exciting coil; d. first and second short-circuited, mutually coaxial secondary turns magnetically coupled to said main magnetic circuit, said first secondary turns being stationary and said second secondary turns being mobile with respect to said first secondary turns in a direction of their common axis; e. an auxiliary magnetic circuit encompassing both said first and secondary turns having a stationary part encompassing a part of said first secondary turns and a mobile part encompassing a part of said secondary turns; and f. a constant air gap separating said stationary and mobile part of said auxiliary magnetic circuit.
 2. The motion electromagnet as set forth in claim 1, having auxiliary turns embedded in surfaces creating the air gap of the auxiliary magnetic circuit.
 3. The motion electromagnet as set forth in claim 1, wherein the relative movement of stationary and mobile parts of said auxiliary magnetic circuit and said first and second secondary turns is linear.
 4. The motion electromagnet as set forth in claim 1 comprising two mutually electrically and magnetically independent main magnetic circuits each having an exciting coil, said switching means alternatively connecting said exciting coils of said two main magnetic circuits to said source of potential at a predetermined rate, a pair of said auxiliary magnetic circuits, adjustable means coupling the mobile parts of said two auxiliary magnetic circuits for adjusting their off-set positions with respect to the corresponding stationary parts of said auxiliary magnetic circuits.
 5. The motion electromagnet as set forth in claim 4, including means for adjusting the speed of said switch means. 